Portable audio system



FIG. 1 is a perspective view of a portable audio system as seen from the front, top, and side;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a side view thereof; and,

FIG. 7 is an opposite side view thereof.

The dotted line portions of the drawings represent environmental structure only and form no part of the claimed design. The broken line showing of numbers, words, and symbols forms no part of the claimed design. 

CLAIM The ornamental design for a portable audio system, substantially as shown and described. 